function powNaive(x, y) { if (!y) return 1; let tmp = x; for (let i = 1; i < y; i++) { tmp *= x; } return tmp;}// from https://codereview.stackexchange.com/a/217369function pow2B(x, y) { if (y < 2) { return y ? x : 1 } if (y & 1) { return x * pow2B(x, y & 0x7FFFFFFE)} const p = pow2B(x, y >> 1); return p * p;}// other two functions from the same stackexchange postfunction pow(x, y) { if (!y) { return 1 } let tmp = res = x; for (let i = 1; i < y; i++) { for (let j = 1; j < x; j++) { tmp += res } res = tmp; } return res;}function pow2(x, y) { if (!y) { return 1; } if (y % 2) { return x * pow2(x, y - 1); } const p = pow2(x, y/2); return p * p;}var x = Math.pow(54, 8);var y = pow2B(54, 8)var y = pow(54, 8)var y = pow2(54, 8)var y = powNaive(54, 8)--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| Math.pow | |
| pow2 bitwise | |
| pow2 summ | |
| pow2 multi | |
| pow (mult for loop) |
| Test name | Executions per second |
|---|---|
| Math.pow | 15784721.0 Ops/sec |
| pow2 bitwise | 7454481.5 Ops/sec |
| pow2 summ | 43277.2 Ops/sec |
| pow2 multi | 5733162.5 Ops/sec |
| pow (mult for loop) | 30622784.0 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net!
Benchmark Definition
The provided JSON represents a benchmark definition for several JavaScript functions that implement exponentiation using different approaches:
powNaive(x, y): A naive recursive implementation with a loop to calculate the power.pow2B(x, y): An iterative implementation using bit manipulation ( bitwise operations).pow2(x, y): Another iterative implementation using bit manipulation.pow(x, y): A summation-based implementation that uses nested loops.Each of these implementations is compared to measure their performance.
Comparison Options
The benchmark tests the following options:
powNaive(x, y) vs. Math.pow(x, y)pow2B(x, y) vs. Math.pow(x, y)pow2(x, y) vs. Math.pow(x, y)pow(x, y) vs. Math.pow(x, y)These comparisons aim to determine which implementation is the most efficient.
Pros and Cons
Here's a brief analysis of each approach:
powNaive(x, y): This recursive implementation has a time complexity of O(y), making it less efficient than other approaches for large exponents.pow2B(x, y): Bit manipulation is an efficient way to calculate powers, especially when dealing with large numbers and exponents. However, the implementation may be less intuitive for those without prior experience with bitwise operations.pow2(x, y): Similar to pow2B, this approach also utilizes bit manipulation but might be slightly more complex due to its use of division instead of AND operation.pow(x, y): This summation-based implementation has a time complexity of O(y * x), which can become inefficient for large exponents or numbers.Other Considerations
Keep in mind that the choice of implementation depends on specific requirements and constraints:
Library Usage
None of the implementations provided use external libraries. However, Math.pow relies on a built-in JavaScript function for exponentiation, which may involve additional overhead not accounted for in this benchmark.
Special JS Features/Syntax
The implementations mentioned earlier do not employ any special JavaScript features or syntax beyond what's standard in modern JavaScript. If these benchmarks were to be modified to utilize features like async/await or modern iteration protocols (e.g., for...of, for...in), it could impact performance.
Now that we've explored the details of this benchmark, feel free to ask any follow-up questions!
